A variety of forced air heat exchangers exist that incorporate a fan, located proximate to fluid-carrying tubes, such as a condenser coil. The fan forces air across the tubes dissipating heat therefrom. Generally, these heat exchangers have a single bank of tubes with a fan located on one side thereof for blowing across the tubes in one direction. Heat exchangers of this type are utilized in a variety of environments including outdoors where the heat exchanger is exposed to dust, dirt, debris and weather. Heat exchangers of this type are utilized in the automotive industry, air conditioning, cryogenics and other moving as well as stationary uses. In many of these applications, debris can accumulate on the tube bank decreasing the efficiency of the heat exchanger. Also, heat exchangers of this type can encounter frost accumulation on the tube bank, also decreasing the efficiency thereof.
In order to clean or defrost the tube bank, various heat exchangers have used a reversible fan that forces the air across the tube bank in two directions; one direction for removing heat from the tube bank and an opposite direction for removing debris or frost therefrom. In these prior art units, the fan is rotated in its heat exchanging mode. As needed, the fan is then reversed to thaw frost from the heat exchange tubes or to remove debris from the tube bank. Until the debris is removed or the frost thawed, the unit is not providing optimum cooling. In effect, then, the heat exchanger is not operating at an acceptable efficiency for a period of time after cycling.
Therefore, a heat exchanger is needed that is self-cleaning without resulting in a period of a non-operativeness of the device.